This is a rare competitive-level thumbnail of schorl, for obvious aesthetic reasons including the quality of the crystal itself, but more importantly for the balance of shapes and colors. Black on white, prism against a “cube” - these give it a unique geometric eye appeal. The feldspar crystal is not a cube, of course, but it is pseudo-cubic and looks like one at first casual glance. From the Desautels Trophy winning collection of Stretch Young, specializing in thumbnails and pseudomorphs.